Control circuit



Feb. 11, 1941. E, M, CLAYTOR 2,231,156

CONTROL CIRCUIT Filed Aug. 21, 1939 2 Sheets-Sheet l QOZV. 12.3.5 02.23 '2524 Mmmomu 054m Feb 11, 1941- y E. M. cLAYToR 2,2%,1456

CONTROL CIRCUIT Filed Aug. 21, 1959 2 Sheets-Sheet 2 l'mnentor du/ald MTU/agio@ Y I CZ ttornegs Patented Feb. 1l, 1941 PATENT OFFICE CONTROL CIRCUIT Edward M. Claytor, Anderson, Ind., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 21, 1939, Serial No. 291,119

13 Claims.

This invention relates to remote controlled automatic means for moving an adjustable control element to a plurality of positions. It particularly concerns protective means for remote controlled automatic tuning mechanism associated with radio communication devices.

In many cases it is desirable to locate a radio receiver at some distance from the control station and provide simple push button means by which the tuning mechanism may be controlled accurately with a minimum amount of manual effort and movement. Apparatus of this type is particularly adapted to radio receiving sets installed on vehicles where space requirements make it necessary to locate the receiver in one position and the controls at another. It is also equally desirable in household installations where the control station location is changed frequently with respect to the receiver or where there are a number of control stations.

It has been found that when the control station is located more conveniently and the manual effort required to operate the controls is reduced, people unauthorized to operate them, particularly children, continue t manipulate the controls which overloads the actuating means.

It has also been found that mechanical detents associated with the controls and automatic indexing mechanism associated with the tuning shaft driving and stopping means stick at times due to the slight clearance between the parts which is necessary for accurate positioning and sharp tuning of the receiving set. When sticking occurs overloading of the driving means likewise occurs and further operation cannot be obtained until repairs are made.

One of the objects of the present invention is to provide positive means for preventing sticking of the indexing means.

Another object is to provide a positive cutout means associated with the driving means to prevent overloading of the driving means.

With these and other objects in view, together with a description of the means by which lthese objects are accomplished, this invention will be better understood by reference to the following specification and claims and illustrated in the accompanying drawings, in which:

Figure l shows in diagrammatic form the complete assembly of the automatic tuning mechanism, the controls associated therewith and electrical connections .between these various elements;

Figures 2 vto 5 are diagrammatic views showing certain of the control elements in various positions, which are as follows:

Figure 2 shows these control elements in their normal or non-controlling position;

Figure 3 shows these elements in a position to establish circuit connections whereby the tuning shaft is rotated in one direction;

Figure 4 shows these elements in a position whereby the circuit connections are changed so that thetuning shaft will be rotated in thereverse direction to that shown in Figure 3; and,

Figure 5 shows these elements in a position to stop rotation of the tuning shaft in a definite angular position and to open all the circuit connections.

A radio receiving set indicated at i has a conventional tuning shaft 3 extending therefrom and a control knob 5 fixed to its extremity for manual rotation thereby. An electridmotor 1 having a worm 9 fixed to an annature`-shaft il meshes with a worm wheel I3 rotatably mounted on the shaft 3. The worm wheel has a hub I5 acting as a clutch driving element. A clutch driven element I1 rotatable with the shaft 3 is suitably biased for axial movement away from the driving gear hub i5. The driven element encloses a magnet winding having end leads i9 and 2| extending therethrough which are connected respectively to motor armature leads 23 and 25.

The magnet' winding is thus connected in parallel with the motor armature and is accordingly energized therewith to cause engagement of the clutch elements I5 and il by electromagnetic attraction between them. The motor has two field windings either of which may be energized by means of conductors 21 or 29 extending therefrom to a control switch indicated at 3i to cause rotation oi the motor in either direction. The clutch lead i9 and armature lead 23 are also connected to the switch 3i by a conductor 33 and the clutch lead 2l and armature lead 25 are connected to a source of energy by control means which will be described later.

The control switch 3| comprises three flexible parallel blades 31,39 and 4i having their adjacent ends clamped between xed insulating blocks 43 and 45 and all three blades are provided with electrical contacts on their free ends. The motor field leads 21 and 29 are respectively connected to the switch blades 4i and 31 and the armature lead 23 and clutch lead I9 are both connected to the central blade 39 by conductors 33 and 34. In addition to the fixed blades the switch has a flexible blade 41 adjacent to and movable into or out of contact with the central blade 39. The

movable blade 41 has a contact on its free end and its opposite end is fixed to a fitting 49 rotatably supported on a stationary'shaft 5| which is grounded at 53. Another rotatable fitting is spaced axially along the shaft 5| and is connected by a switch actuating rod 51 having bent end portions 59 and 6| fixed respectively to the fittings 49 and 53. A tension spring 63 located between the rod end 59 and a fixed member 35 normally tends to rotate the rod 51 and free end of the switch blade 41 clockwise about the shaft 5| and into contact with the central switch blade 39 bending it upward into contact with the upper blade 31 as shown in Figure 2. Movement of the switch blade counterclockwise is accomplished by the following actuating mechanism.

lThe motor control switch actuating mechanism comprises a fixed supporting shaft 61 located above and parallel to the shaft 5|. On the shaft 5| are pivoted any number of axially spaced armatures, two of which, 69 and 69a, are shown, and a single knockout armature 1|. The armatures 69 and 69a extend downwardly on the right of the switch actuating rod 51 and have helical tension springs 13 and 13a fixed between pins 15 and 15a on their upper ends and a fixed rod 11 which tend to normally rotate these armatures counterclockwise about the shaft 61 into contact with a fixed stop rod 19. The actuating rod 51 is normally held by its spring 63 in contact with the left side of the downward extending armatures 69 and 59a when the right sides of these armatures are against the stop rod 19. The knockout armature 1| extends downwardly on the opposite or left side of the actuating rod 51 and is normally held in contact therewith by a tension spring 8| connected between a hooked portion 82 and the fixed rod 11. The normal position of the knockout armature is best shown in Figure 2.- The armatures 59 and 69a, together with the knockout armature 1|, are movable clockwise about the shaft 61 from their normal position by fixed electromagnets, each of which is located adjacent the respective armatures and indicated at 83, 83a and 95. One end of each of these electromagnetic windings is grounded at points 81, 81a and 89 and the other ends thereof, 9|, 9|a and 93, extend to control apparatus to be referred to subsequently. The armatures 69 and 69a each have end portions 95 and 95a bent at right angles thereto which act as cam followers to contact cams 91 and 91a located adjacent thereto when these armatures are moved toward the cams by the respective electromagnets 83 and 83a.

'The cams 91 and 91a have arcuate portions 99 and 99a of small radius and arcuate portions |0| and iia rof larger radius and radial slots |93 and |0311. The cams are fixed to a camshaft |05 by set screws |01 and |01a and may be adiusted to different angular positions thereon. The camshaft |05 is mounted for rotation about its axis, which extends parallel to the switch actuating rod 51, by means of the gears |09 and of equal pitch diameters running in constant mesh and fixed respectively to the camshaft |05 and the tuning shaft 3. The ends 95 and, 95a of these armatures are movable into sliding contact with either of the arcuate portions of the cams and are capable of entering the slots between to stop rotation of the camshaft and tuning shaft in a definite angular position, depending upon the angular position the cams are set with respect to the camshaft and which armature is moved toward its respective cam by its respective electromagnet. The end 95 of the armature Il is shown in the radial slot |93 of the cam 91 to stop rotation of the cam and tuning shafts and the switch actuating rod has been moved counterclockwise thereby to its maximum angular position so that the movable switch blade 41 which is grounded at 53 is moved out of contact wlth'the fixed blade 39 `of the switch 3|. This is the open circuit position of the switch 3|, as shown in Figures 1 and 5, which deenergizes the clutch winding and driving motor. When the end 95 of the armature is moved into contact with the arcuate surface 99 of the cam, as shown in Figure 4, the movable switch blade 41 is moved into contact with the fixed blades 39 and 4| to connect the field lead 21 to conductors 33 and 34 which are connected to the armature lead 23 to cause rotation of the motor in a direction so that the tuning shaft will be rotated in one direction and the cam 91 will be moved clockwise as shown by the arrow. When' the end 95 of the armature is moved into contact with the arcuate surface IDI of the cam, as shown in Figure 3, the movable switch blade 41 moves` the fixed blade 39 out of contact with the blade 4| and into contact with the blade 31 which connects the other field lead 29 to the armature to cause rotation of the motor in the opposite direction which rotates the cam 91 counterclockwise as indicated by the arrow. 'I'he switch blades 31, 39 and 41 are also in contact when the actuating rod 51 and the armatures 59 and 39a are returned to their normal noncontrolling position as indicated in Figure 2.

As mentioned above, any number of cams and armatures may be used so that the tuning shaft may be moved to any one of a plurality of angular positions, each of which may be adjusted by rotating any particular cam angularly with respect to the camshaft, Each of the electromagnets operating the armatures may be selectively energized as they are included in separate circuits, each of which also includes a manually operable selector switch. Any one of these switches in addition to energizing any one of the armatures simultaneously energizes the electromagnet 85 of the knockout armature and holding coils, one of which energizes the motor and clutch windings and another of which grounds the radio speaker circuit in the following manner.

Two selector switches ||3 and ||3a are shown, both comprising identical parts, and are similarly connected in separate parallel circuits. Identical parts and connections are indicated by the same numerical characters included in both circuits, but may be separately identified as the parts and connections in one circuit carry a subscript A after the numerical characters. The switch H3 comprises an armature ||5 manually movable to bridge three adjacent contacts ||1, ||9 and |2| but is normally biased to the open position. The contact ||1 is connected by conductors |23 and |25 to the radio power supply which may be a battery having one terminal grounded. The contact |i 9 is connected by a conductor 9| to the electromagnet 83, the other side of which is grounded at 81. Energization of the electromagnet 83 attracts the armature 69 which moves the switch blade 41 from the position shown in Figure 2 to any of the positions shown in Figures 3 to 5. The contact |2| is connected to a fixed terminal support |3| of a thermal switch |33 by conductors |21 and |29. This switch comprises a bimetaliic blade |35, one end of which is fixed to the support I 3| and the other is normally in contact with an adjacent contact |36, but when heated it expands and breaks this contact. Conductors 93 and |31 iixed to and extending from the' contact |36 are connected respectively to the knockout electromagnet 35, the other side of which is grounded at 99 and to holding coils |39, `|39a and |4|. The opposite ends of these coils are connected to the central tixed blade 39 of the switch 3| by a common conductor |43 and the conductor 34. The knockout armature 1| is attracted to the electromagnet 95 when the above circuit is thus energized and the holding coils |39, |39a and |4| are simultaneously energized. The holding coils |39 and |39a are located when the central blade 39 is in contact with the movable blade 49, as shown in Figures 2 and 3, to attract the armatures ||5 and I|5a of the selector switches 3 and ||3a respectively, as shown by the dotted lines in Figure 1, and are designed so that they exert Just suflicient attractive effort to hold these respective armatures in their closed circuit position so that whichever armature has been closed manually remains closed.

Another armature |45 located adjacent to the holding coil |39 is connected to the source of power by the conductors |25 and |41 and is attracted and moved toward the holding-coil |39 as shown by the dotted lines and into contact with a xed contact |49 located adjacent thereto. Closure of this armature energizes the motor and clutch circuits through a resistance heating ele- 'ment |5| located adjacent the bimetallic blade |35 of the thermal switch |33. The heater element is connected to the contact |48 by a conductor |49 and to one side of the electromagnetic clutch winding and armature winding by the conductor 35. The opposite Vsides of the clutch winding and armature winding respectively are both connected to the central blade 39 of the switch 3| by the conductors 33 and 34. The holding coil |4| when energized attracts an arma'- ture |53 which is grounded at |55, moving it into contact with a nxed contact |51. A conductor |59 attached to this contact |51 extends from the speaker associated with the radio receiver and is grounded when the armature |53 is closed to ground the speaker circuit and mute it while the tuning shaft is being rotated by the motor.

The operation of the automatic tuning mechanism and protective devices associated therewith is as follows: Closure of any selector switch, for example, ||3a, completes a circuit from the source of power-through the electromagnet 83a to ground at 91a to attract and move the armature 59a from its normal postion. as shown in Figures 1 and 2, toward the cam 91a. Its movement is limited by its end 95a contacting with the arcuate cam surface ||a of large radius which causes it to contact and move the switch actuating bar 51 and switch blade 41 so that the switch blades 31, 39 and 41 are moved to the position shown in Figure 3. This position of the switch blades makes the proper motor field connection to cause rotation of the tuning shaft in one direction and rotation of the camshaft in a counterclockwlse direction. The holding coils |39a, |39 and |4| and the electromagnet 85 are` simultaneously energized to hold the armature ||a of the switch closed, to move the armature |45 into contact with the contact |48 energizing the motor and clutch windings, and to move the knockout armature clockwise out of contact with the switch actuating rod 51, the'knockout armature 1| taking a position as shown in Figure 5.

The tuning shaft rotation continues until the end 95a of the armature 69a moves to the bottom of the radial slot |03a of the cam which causes the switch 3| to open and open al1 of the above circuits, stopping the tuning shaft in this particular angular position. All the control elements are accordingly returned to their normal position, as shown in Figure 2, by their respective biasing springs. Should however the armature end 95a bind in the slot |03a in this position, the knockout armature 1| will strike the switch actuating rod 51 upon its return tothe normal position to move the armature 69a toward its normal position to eject its end 95a from thel slot |0311. Thus the knockout armature prevents binding between these elements and if not pro'-l vided it would be impossible to again energize the motor and clutch windings until these elements were freed to allow the switch blades to assume their normal position for reenergization of the motor and clutch by any selector switch.

This is normal operation for counterclockwise.

rotation of the cam. Rotation of the tuning shaft in the opposite direction, which causes clockwise rotation of the cams, is obtained when the armature end contacts the arcuate cam surface 99a which moves the blade 41 so that blades 39, 4| and 41 are in contact, as shown in Figure 4, to connect the other motor eld winding in a similar manner as explained above.

Should the end 95a bind and stop inthe radial cam slot |03a before bottoming, the rotating tuning shaft would be stopped but the motor switch would not be opened and the increased motor current passing through the heating elementv |5| would cause an increase in heat therefrom to open the thermal switch |33. Opening of this switch also opens all circuits and the knockout amature again acts to eject the dog end upon its return to the normal position.

If the selector switches are continuously operated to cause the motor to be started and stopped ior long periods of time, the current through the heater |5| will cause the heat therefrom to open the thermal switch |33 to prevent damage to the motor.

I claim:

l. In an automatic tuning device'or radio communication systems comprising a motor, a tuning shaft connected to the motor for rotation thereby, a member connected to and rotated by the shafthaving a slot in its surface, a second member movable with respect to the first member into contact therewith and adapted to enter the slot to stop rotation of the shaft in a denite angular position, electromagnetic means for moving the second member, knock out means for ejecting said second member from the slot in said first member, electromagnetic means for moving said knock out means to allow movement of said second member into the slot in said rst member, a source of current and means for connecting the motor and both of said electromagnetic means to the source of current, said means including disconnecting means operable upon abnormal values of current iiowing therethrough.

2. In an automatic tuning device for radio communication systems comprising a motor, a tuning shaft connected thereto for rotation thereby, a member-connected to and rotated by the shaft having a slot in its surface, a second member normally held'out of contact with the first member but movable into engagement with the slot in the ilrst member to stop rotation of illl the shaft, electromagnetic means for moving the second member, knock out means for ejecting said second member from the slot in said first member, electromagnetic means for moving said knock out means to prevent ejection of said second member, a source of current, and means for connecting the motor and both of said electromagnetic means to the source of current, said means including disconnecting means movable by the second member entering the `slot in the first member to denergize and stop rotation of the motor.

3. In an automatic tuning device for radio communication systems comprising a motor, a tuning shaft connected thereto for rotation thereby, a member connected to the shaft for rotation thereby having a slot in its surface, a second member normally held out of engagement with the first mentioned member but movable into engagement with a slot therein to stop rotation of the tuning shaft in a definite angular position, electromagnetic means for moving said second member, a third member normally held in contact with the second member and movable therewith, a fourth member normally held in contact with the third member but movable away from both the second and third members, electromagnetic means for moving said fourth member, a source of current, means for connecting both electromagnetic means and the motor to the source of current, and disconnecting means in said last mentioned means operably connected to the third member to disconnect the motor and both lelectromagnetic means to allow the fourth member to strike the third member to eject the second member from the slot in the first mentioned member.

4. In an automatic tuning device -ior radio communication systems comprising a tuning shaft, a motor connected thereto to rotate the shaft, a member connected to the shaft for rotation thereby having a slot in its surface, a second member movable into engagement with the slot in the first mentioned member to stop rotation of the shaft, a third member normally held in contact with the second member holding it out of contact with the first member, a fourth member normally heldin contact with the third member but movable out of contact therewith, electromagnetic means for moving the second and fourth members. a source of current, means for connecting the electromagnetic means and the motor to the source of current, disconnecting means included in said last mentioned means operably connected to the third member and movable by said second member entering fully into the slot of the rst member and additional disconnecting means operable by excessive motor current through the connecting means upon failure of the second member to break these connections, both of said disconnecting means .causing the second member to be ejected from the first named member uponreturn of the fourth member to its normal position. l

5. In an automatic tuning device for radi communication systems comprising an electric motor, a tuning shaft connected to the motor for rotation thereby, a member connected to and rotated by the shaft having a slot in its surface, a second member normally held out of contact with the first member but movable into the slot therein to stop rotation of the tuning shaft in a preselected angular position, an electromagnet for moving said second member, a source of current, a circuit from said source to the eleccircuits to open them when the current in said' second circuit exceeds a safe value.

6. In an automatic tuning device for radio communication systems comprising an electric motor, a tuning shaft connected to the motor for rotation thereby, a member connected to and rotated by the shaft having a slot in its surface, a second member normally held out of contact with the first member butmovabie into the slot therein to stop rotation of the tuning shaft in a preselected angular position, an electromagnet for moving said second member, a source of current, a circuit from said source to said motor includinga control switch normally closed and operably connected to and movable by the second member to open said circuit, an armature switch normally open but movable to close said circuit, a control circuit connected to said source including a holding coil adjacentsaid armature switch to attract and move it, and a selector switch normally open but manually movable to close said circuit through said electromagnet and control switch, said selector switch being located adjacent to said holding coil to attract and hold it closed until said tuning shaft is rotated to said preselected position.

7. In an automatic tuning device for radio communication systems comprising an electric motor, a tuning shaft connected to the motor for rotation thereby, a member connected to andl rotated by the shaft having a slot in its surface, a second member normally held out of contact with the first member but movable into the slot therein to stop rotation of the tuning shaft in a preselected angular position, an electromagnet for moving said second member, a source of current, a circuit from said source to said motor including an armature switch normally open but movable to close said circuit to cause rotation of the tuning shaft, a control circuit connected between said source and the electromagnet including a holding coil adjacent said armature switch to attract and move it to its closed position and a selector switch adjacent the holding coil manually movable to its closed position at which it is held by the holding coil to complete said control circuit, a disconnecting means through which both of said circuits are normally completed having a movable member operably connected for movement with the second member to open these circuits when said second member enters and bottoms in the slot in the first member and thermal disconnecting-means common to both said circuits to open said control circuit upon abnormal current flow in the first circuit due to failure of the first named disconnecting means to open said first circuit when the tuning shaft is stopped thereby.

8. In an automatic tuning device for radio communication systems comprising an electric motor, a tuning shaft connected to the motor for rotation thereby, a member having surfaces of different radii separated by a slot driven by the tuning shaft. a second member movable into contact with either surface and capable of entering second power means the energization of which is controlled by said first named control means to move said member to allow engagement with any cam by any cam follower and the de-energization of which is controlled by said second control means to cause any cam follower to be knocked out of contact with any cam.

13. In a device for angularly indexing a rotatable shait, a motor for driving said shaft, cut out' means for said motor operative on overload to cle-energize and stop rotation thereof, means for controlling energization, (ie-energization and reversal of said motor and for stopping rotation of said shaft, said means comprising a plurality of cams rotatable with said shaft, a cam follower for each cam normally biased out of engagement therewith, an individual electromagnet adapted when energized for moving and holding each follower in contact with a respective cam, a plurality of switched-each of which is operable to control energization of one of said electromagnets, a second switch operable by movement of any cam follower for controlling the duration of energizatlon of any electromagnet and said motor, and knock out means for said cam followers comprising a member biased to engage and hold said cam followers disengaged from said cams, an electromagnet energizable by any one of said first named switches to attract and hold said member out oi' contact with said followers, de-

energlzation of said last mentioned electromag net being controlled by said second named switch and said motor cut out means to cause said member to strike said cam followers and return them to their normally disengaged position.

EDWARD M. CLAYTOR. 

